scholarly journals Stability Analysis of TBM Tunnel Undercrossing Existing High-Speed Railway Tunnel: A Case Study from Yangtaishan Tunnel of Shenzhen Metro Line 6

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Mingji Zhao ◽  
Yun Cheng ◽  
Zhanping Song ◽  
Tong Wang ◽  
Yuwei Zhang ◽  
...  
Keyword(s):  
High Speed ◽  
Development Trend ◽  
Surrounding Rock ◽  
Deformation Characteristics ◽  
Horizontal Deformation ◽  
Railway Tunnel ◽  
Monitoring Method ◽  
Maximum Settlement ◽  
Maximum Deformation ◽  
Unloading Effect

During the construction of the underpass of a new tunnel, the excavation unloading effect disturbs surrounding rock masses and promotes surrounding rock deformation, inevitably changing stress and displacement in the existing tunnel. Taking Yangtaishan tunnel excavation of Shenzhen Metro Line 6 as an engineering example, effects of excavation programs of left and right lines on the deformation characteristics of newly excavated and existing tunnels were evaluated based on Midas numerical model and priority excavation advantages of the left line were determined. The settlement and horizontal deformation characteristics of the existing tunnel were analyzed using the construction monitoring method. Results showed that maximum settlement and horizontal deformation of the existing tunnel were 1.35 and 0.23 mm, respectively. Settlement of invert and inverted top along axis direction was from growth to decline, and then a V-shaped settlement trough was formed with maximum settlement values of 1.36 and 0.97 mm, respectively. Maximum settlement and uplift of the newly built tunnel appeared on the upper and bottom parts of invert, respectively. In the newly built tunnel segments, the top settlement was dominated and deformation was mainly distributed in both side areas. At the top of the existing tunnel segment, convergence settlement was 3.09 mm and settlement rate was slow first which was accelerated, then stabilized, and finally slowed down again which was opposite to the uplift development trend of the bottom of tunnel segment. The top of the existing tunnel segment showed four settlement stages, slow, rapid, stable, and slow settlement stages. Compared with the right line, preferential excavation of the left line had obvious advantages in terms of tunnel stability. The unloading effect of TBM excavation created vault settlement in the existing tunnels where actual settlement values were 1.12 and 1.13 times, which theoretically calculated settlement. The horizontal deformation of the existing tunnel was varied first linearly and then nonlinearly with maximum deformation in the convergence stage of 1.47 mm.

Instability Mechanism of Surrounding Rock for Super-Large Cross Section at High-Speed Railway Tunnel Portal

2013 ◽  
Vol 353-356 ◽  
pp. 1597-1603
Author(s):  
Shuang Lan Wu ◽  
Shi Hao Yang ◽  
Xue Wen Zhang
Keyword(s):  
High Speed ◽  
Surrounding Rock ◽  
Instability Mechanism ◽  
Large Cross Section ◽  
Railway Tunnel ◽  
High Speed Railway ◽  
Construction Procedure ◽  
In Situ Conditions ◽  
Major Factors

Difficulties of tunnel construction mainly appear in the entrance and exit stage, some adverse geological problems may occur. In terms of the tunnel at the Changsha-Kunming section of the Shanghai-Kunming passenger line, firstly, adverse geological phenomena at tunnel exits was described. Secondly, major factors leading to disasters were listed, including geology, hydrology and construction procedure. Combined with in-situ conditions, Finite Element Method (FEM) was used to analyze the instability mechanism of surrounding rock after the upper arch gate was excavated by three-bench seven-step exaction method. At last, through comparison between computed result and measuring data, several basic conclusions was obtained. It can make much sense to similar engineering.

scholarly journals Information-Based Construction of High-Speed Railway Tunnel

2017 ◽  
Vol 2017 ◽  
pp. 1-11
Author(s):  
Qian Yang ◽  
Zhaoling Wang
Keyword(s):  
High Speed ◽  
Calculation Model ◽  
Surrounding Rock ◽  
Rock Properties ◽  
Design Parameters ◽  
Model Parameters ◽  
Railway Tunnel ◽  
Long Distance ◽  
Tunneling Model ◽  
High Speed Railway

Nowadays, railway tunnel construction faces huge developments and opportunities, with a tendency for high speed and long distance. How to effectively apply the information in the construction process has been the focus of current research. According to the Xian-nvyan tunnel in Xicheng high-speed railway, our research was based on the geological forecast, selecting appropriate tunneling model parameters to establish the 3D calculation model. Through the numerical simulation of three tunnel excavation and support methods, we analyzed the displacement of surrounding rock and the plastic failure to select the construction method reasonably. Compared with the actual measured data, we judged the rationality of the selected scheme and model parameters, so as to provide design parameters which conform to the surrounding rock properties for the subsequent construction, thus optimizing the construction program and applying the concept of information-based construction in engineering actually.

The Interaction Mechanism of Surrounding Rock and Supporting Structure in High Geostress Extrusion Fault

2011 ◽  
Vol 243-249 ◽  
pp. 3588-3598 ◽  
Author(s):  
Zhi Min Chen ◽  
De An Zhao ◽  
Yun Yan Yu
Keyword(s):  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Surrounding Rock ◽  
Deformation Characteristics ◽  
Horizontal Deformation ◽  
Support Structure ◽  
Supporting Structure ◽  
Lateral Pressure Coefficient ◽  
Geological Conditions ◽  
High Geostress

Muzhailing tunnel of Lanyu railway is located in the western part of Qinling Mountain, its geological conditions are very complex. There is an extrusion fault, f16, in the Dazhangou inclined shaft, and the strata are consist of slate, sandston and carbonaceous slate. The measured geostress results showed that this location is in a very high level of geostress state, the maximum horizontal principal geostress is nearly vertical to Dazhangou inclined shaft and the measured horizontal lateral pressure coefficient is 3.79. Soft rock crushing, high geostress state, high horizontal lateral pressure coefficient and other factors led to the poor stability for the shaft. During the construction process of the shaft, the deformation characteristics are showed as strong horizontal deformation, rapid and large rate initial deformation, and long duration. According to rock lithology conditions, geostress conditions, supporting structure and dynamic construction, deformation characteristics of the shaft, the large horizontal deformation was caused by the interaction of high horizontal lateral pressure coefficient and poor geological conditions and other factors, but the main reasons of the large horizontal deformation were recognized as uneven vertical and horizontal load, extreme adverse load conditions of support structure, based on the theoretical and 3D numerical analysis. Through the analysis of the interaction of support structure and the surrounding rock, the smaller deformation in front of the working face during tunnel excavation is took place, the less stress release would be took place and the larger the ultimate load would be on the support structure. Tremendous stress was withstood by the arch crown, larger wall tensile stress was appeared at side wall, the support structure is in a poor stress state. This paper provides a theoretical basis for dynamic design and construction of the Dazhangou inclined shaft and Muzhailing tunnel.

Recent Patents on the Angular Contact Ball Bearing of High-Speed Motorized Spindle

2020 ◽  
Vol 13 ◽  
Author(s):  
Yudong Bao ◽  
Linkai Wu ◽  
Yanling Zhao ◽  
Chengyi Pan
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Rapid Development ◽  
Ceramic Materials ◽  
Development Trend ◽  
Numerical Control ◽  
Angular Contact Ball Bearing ◽  
Practical Applications ◽  
High Speed Cutting ◽  
Advantages And Disadvantages

Background:: Angular contact ball bearings are the most popular bearing type used in the high speed spindle for machining centers, The performance of the bearing directly affects the machining efficiency of the machine tool, Obtaining a higher value is the direction of its research and development. Objective:: By analyzing the research achievements and patents of electric spindle angular contact bearings, summarizing the development trend provides a reference for the development of electric spindle bearings. Methods:: Through the analysis of the relevant technology of the electric spindle angular contact ball bearing, the advantages and disadvantages of the angular contact ball bearing are introduced, and the research results are combined with the patent analysis. Results:: With the rapid development of high-speed cutting and numerical control technology and the needs of practical applications, the spindle requires higher and higher speeds for bearings. In order to meet the requirements of use, it is necessary to improve the bearing performance by optimizing the structure size and improving the lubrication conditions. Meanwhile, reasonable processing and assembly methods will also have a beneficial effect on bearing performance. Conclusion:: With the continuous deepening of bearing technology research and the use of new structures and ceramic materials has made the bearing's limit speed repeatedly reach new highs. The future development trend of high-speed bearings for electric spindles is environmental protection, intelligence, high speed, high precision and long life.

Review of Research on Hydrostatic Bearings

2020 ◽  
Vol 13 ◽  
Author(s):  
Xiaodong Yu ◽  
Yu Wang ◽  
Junfeng Wang ◽  
Wenkai Zhou ◽  
Hongwei Bi ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Development Trend ◽  
Cnc Machining ◽  
Pressure Effects ◽  
Cnc Machine Tools ◽  
Future Research ◽  
Theoretical Formula ◽  
Hydrostatic Bearing ◽  
Hydrostatic Bearings

Background: Hydrostatic bearings have the advantages of strong bearing capacity, good stability, small friction coefficient and long life. The performance of liquid hydrostatic bearings directly affect the accuracy and efficiency of CNC machining equipment. The performance is conducive to the development of CNC machine tools towards high speed and heavy load, so it is necessary to sort out and summarize the existing research results. Objective: This study summarizes the current development status of hydrostatic bearings and explains the development trend of hydrostatic bearings. Methods: According to the recently published journal articles and patents, the recent experimental research on hydrostatic thrust bearings is summarized. This paper summarizes many factors that affect the performance of hydrostatic bearings, and discusses the causes of various factors on hydrostatic bearings. Finally, future research on hydrostatic bearings is presented. Results: The study discusses experimental methods, simulation processes, and experimental results. Conclusion: This study can produce dynamic and static pressure effects by changing the structure of the oil cavity of the hydrostatic bearing. This effect can make up for the static pressure loss. By improving the theoretical formula and mathematical model and proposing a new simulation method, the accuracy of the hydrostatic bearing simulation is satisfied; the future development trend of the hydrostatic bearing is proposed.

scholarly journals Development of a wind turbine gearbox virtual load sensor using multibody simulation and artificial neural networks

2021 ◽  
Author(s):  
Baher Azzam ◽  
Ralf Schelenz ◽  
Björn Roscher ◽  
Abdul Baseer ◽  
Georg Jacobs
Keyword(s):  
Time Series ◽  
Wind Turbine ◽  
High Speed ◽  
Time Series Data ◽  
Development Trend ◽  
Series Data ◽  
Ann Model ◽  
Wind Turbine Gearbox ◽  
Virtual Sensor ◽  
Artificial Neural

AbstractA current development trend in wind energy is characterized by the installation of wind turbines (WT) with increasing rated power output. Higher towers and larger rotor diameters increase rated power leading to an intensification of the load situation on the drive train and the main gearbox. However, current main gearbox condition monitoring systems (CMS) do not record the 6‑degree of freedom (6-DOF) input loads to the transmission as it is too expensive. Therefore, this investigation aims to present an approach to develop and validate a low-cost virtual sensor for measuring the input loads of a WT main gearbox. A prototype of the virtual sensor system was developed in a virtual environment using a multi-body simulation (MBS) model of a WT drivetrain and artificial neural network (ANN) models. Simulated wind fields according to IEC 61400‑1 covering a variety of wind speeds were generated and applied to a MBS model of a Vestas V52 wind turbine. The turbine contains a high-speed drivetrain with 4‑points bearing suspension, a common drivetrain configuration. The simulation was used to generate time-series data of the target and input parameters for the virtual sensor algorithm, an ANN model. After the ANN was trained using the time-series data collected from the MBS, the developed virtual sensor algorithm was tested by comparing the estimated 6‑DOF transmission input loads from the ANN to the simulated 6‑DOF transmission input loads from the MBS. The results show high potential for virtual sensing 6‑DOF wind turbine transmission input loads using the presented method.

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